Whole house humidifier, manufactured by Research Products Corp. The Model 558 bypass humidifier offers the flexibility of easy installation on either warm air supply or cold air return on any forced air furnace. This model is equipped with a drain to flush minerals and solid residue out of the system. Comes with the digital AutoTrac control system. This system is so advanced it raises and lowers the humidity set point as the weather changes for optimum comfort.

* Calculations based on (1) 20?F. and 70% R.H. Outside Air. (2) 70?F. and 35% R.H. Room Air. (3) Internal Moisture Gain of 1lb./hr. (4) 70% Blower Operation. (5) 8 ft. ceiling height.